1// Components for manipulating non-owning sequences of characters -*- C++ -*-
3// Copyright (C) 2013-2023 Free Software Foundation, Inc.
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
25/** @file include/string_view
26 * This is a Standard C++ Library header.
30// N3762 basic_string_view library
33#ifndef _GLIBCXX_STRING_VIEW
34#define _GLIBCXX_STRING_VIEW 1
36#pragma GCC system_header
38#if __cplusplus >= 201703L
40#include <bits/char_traits.h>
41#include <bits/functexcept.h>
42#include <bits/functional_hash.h>
43#include <bits/range_access.h>
44#include <bits/stl_algobase.h>
45#include <ext/numeric_traits.h>
47#if __cplusplus >= 202002L
48# include <bits/ranges_base.h>
53# include <bits/ostream_insert.h>
56namespace std _GLIBCXX_VISIBILITY(default)
58_GLIBCXX_BEGIN_NAMESPACE_VERSION
61# define __cpp_lib_string_view 201803L
64#if __cplusplus > 201703L
65# define __cpp_lib_constexpr_string_view 201811L
68 // Helper for basic_string and basic_string_view members.
70 __sv_check(size_t __size, size_t __pos, const char* __s)
73 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
74 "(which is %zu)"), __s, __pos, __size);
78 // Helper for basic_string members.
79 // NB: __sv_limit doesn't check for a bad __pos value.
81 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
83 const bool __testoff = __off < __size - __pos;
84 return __testoff ? __off : __size - __pos;
88 * @class basic_string_view <string_view>
89 * @brief A non-owning reference to a string.
94 * @tparam _CharT Type of character
95 * @tparam _Traits Traits for character type, defaults to
96 * char_traits<_CharT>.
98 * A basic_string_view looks like this:
105 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
106 class basic_string_view
108 static_assert(!is_array_v<_CharT>);
109 static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
110 static_assert(is_same_v<_CharT, typename _Traits::char_type>);
115 using traits_type = _Traits;
116 using value_type = _CharT;
117 using pointer = value_type*;
118 using const_pointer = const value_type*;
119 using reference = value_type&;
120 using const_reference = const value_type&;
121 using const_iterator = const value_type*;
122 using iterator = const_iterator;
123 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
124 using reverse_iterator = const_reverse_iterator;
125 using size_type = size_t;
126 using difference_type = ptrdiff_t;
127 static constexpr size_type npos = size_type(-1);
129 // [string.view.cons], construction and assignment
132 basic_string_view() noexcept
133 : _M_len{0}, _M_str{nullptr}
136 constexpr basic_string_view(const basic_string_view&) noexcept = default;
138 [[__gnu__::__nonnull__]]
140 basic_string_view(const _CharT* __str) noexcept
141 : _M_len{traits_type::length(__str)},
146 basic_string_view(const _CharT* __str, size_type __len) noexcept
147 : _M_len{__len}, _M_str{__str}
150#if __cplusplus >= 202002L && __cpp_lib_concepts
151 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
152 requires same_as<iter_value_t<_It>, _CharT>
153 && (!convertible_to<_End, size_type>)
155 basic_string_view(_It __first, _End __last)
156 noexcept(noexcept(__last - __first))
157 : _M_len(__last - __first), _M_str(std::to_address(__first))
160#if __cplusplus > 202002L
161 template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
162 requires (!is_same_v<_DRange, basic_string_view>)
163 && ranges::contiguous_range<_Range>
164 && ranges::sized_range<_Range>
165 && is_same_v<ranges::range_value_t<_Range>, _CharT>
166 && (!is_convertible_v<_Range, const _CharT*>)
167 && (!requires (_DRange& __d) {
168 __d.operator ::std::basic_string_view<_CharT, _Traits>();
171 basic_string_view(_Range&& __r)
172 noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
173 : _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
176 basic_string_view(nullptr_t) = delete;
180 constexpr basic_string_view&
181 operator=(const basic_string_view&) noexcept = default;
183 // [string.view.iterators], iterator support
186 constexpr const_iterator
187 begin() const noexcept
188 { return this->_M_str; }
191 constexpr const_iterator
193 { return this->_M_str + this->_M_len; }
196 constexpr const_iterator
197 cbegin() const noexcept
198 { return this->_M_str; }
201 constexpr const_iterator
202 cend() const noexcept
203 { return this->_M_str + this->_M_len; }
206 constexpr const_reverse_iterator
207 rbegin() const noexcept
208 { return const_reverse_iterator(this->end()); }
211 constexpr const_reverse_iterator
212 rend() const noexcept
213 { return const_reverse_iterator(this->begin()); }
216 constexpr const_reverse_iterator
217 crbegin() const noexcept
218 { return const_reverse_iterator(this->end()); }
221 constexpr const_reverse_iterator
222 crend() const noexcept
223 { return const_reverse_iterator(this->begin()); }
225 // [string.view.capacity], capacity
229 size() const noexcept
230 { return this->_M_len; }
234 length() const noexcept
239 max_size() const noexcept
241 return (npos - sizeof(size_type) - sizeof(void*))
242 / sizeof(value_type) / 4;
247 empty() const noexcept
248 { return this->_M_len == 0; }
250 // [string.view.access], element access
253 constexpr const_reference
254 operator[](size_type __pos) const noexcept
256 __glibcxx_assert(__pos < this->_M_len);
257 return *(this->_M_str + __pos);
261 constexpr const_reference
262 at(size_type __pos) const
265 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
266 "(which is %zu) >= this->size() "
267 "(which is %zu)"), __pos, this->size());
268 return *(this->_M_str + __pos);
272 constexpr const_reference
273 front() const noexcept
275 __glibcxx_assert(this->_M_len > 0);
276 return *this->_M_str;
280 constexpr const_reference
281 back() const noexcept
283 __glibcxx_assert(this->_M_len > 0);
284 return *(this->_M_str + this->_M_len - 1);
288 constexpr const_pointer
289 data() const noexcept
290 { return this->_M_str; }
292 // [string.view.modifiers], modifiers:
295 remove_prefix(size_type __n) noexcept
297 __glibcxx_assert(this->_M_len >= __n);
303 remove_suffix(size_type __n) noexcept
305 __glibcxx_assert(this->_M_len >= __n);
310 swap(basic_string_view& __sv) noexcept
317 // [string.view.ops], string operations:
321 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
323 __glibcxx_requires_string_len(__str, __n);
324 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
325 const size_type __rlen = std::min<size_t>(__n, _M_len - __pos);
326 // _GLIBCXX_RESOLVE_LIB_DEFECTS
327 // 2777. basic_string_view::copy should use char_traits::copy
328 traits_type::copy(__str, data() + __pos, __rlen);
333 constexpr basic_string_view
334 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
336 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
337 const size_type __rlen = std::min<size_t>(__n, _M_len - __pos);
338 return basic_string_view{_M_str + __pos, __rlen};
343 compare(basic_string_view __str) const noexcept
345 const size_type __rlen = std::min(this->_M_len, __str._M_len);
346 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
348 __ret = _S_compare(this->_M_len, __str._M_len);
354 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
355 { return this->substr(__pos1, __n1).compare(__str); }
359 compare(size_type __pos1, size_type __n1,
360 basic_string_view __str, size_type __pos2, size_type __n2) const
362 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
365 [[nodiscard, __gnu__::__nonnull__]]
367 compare(const _CharT* __str) const noexcept
368 { return this->compare(basic_string_view{__str}); }
370 [[nodiscard, __gnu__::__nonnull__]]
372 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
373 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
377 compare(size_type __pos1, size_type __n1,
378 const _CharT* __str, size_type __n2) const noexcept(false)
380 return this->substr(__pos1, __n1)
381 .compare(basic_string_view(__str, __n2));
384#if __cplusplus > 201703L
385#define __cpp_lib_starts_ends_with 201711L
388 starts_with(basic_string_view __x) const noexcept
389 { return this->substr(0, __x.size()) == __x; }
393 starts_with(_CharT __x) const noexcept
394 { return !this->empty() && traits_type::eq(this->front(), __x); }
396 [[nodiscard, __gnu__::__nonnull__]]
398 starts_with(const _CharT* __x) const noexcept
399 { return this->starts_with(basic_string_view(__x)); }
403 ends_with(basic_string_view __x) const noexcept
405 const auto __len = this->size();
406 const auto __xlen = __x.size();
407 return __len >= __xlen
408 && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
413 ends_with(_CharT __x) const noexcept
414 { return !this->empty() && traits_type::eq(this->back(), __x); }
416 [[nodiscard, __gnu__::__nonnull__]]
418 ends_with(const _CharT* __x) const noexcept
419 { return this->ends_with(basic_string_view(__x)); }
422#if __cplusplus > 202002L
424 // This FTM is not freestanding as it also implies matching <string>
425 // support, and <string> is omitted from the freestanding subset.
426# define __cpp_lib_string_contains 202011L
430 contains(basic_string_view __x) const noexcept
431 { return this->find(__x) != npos; }
435 contains(_CharT __x) const noexcept
436 { return this->find(__x) != npos; }
438 [[nodiscard, __gnu__::__nonnull__]]
440 contains(const _CharT* __x) const noexcept
441 { return this->find(__x) != npos; }
444 // [string.view.find], searching
448 find(basic_string_view __str, size_type __pos = 0) const noexcept
449 { return this->find(__str._M_str, __pos, __str._M_len); }
453 find(_CharT __c, size_type __pos = 0) const noexcept;
457 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
459 [[nodiscard, __gnu__::__nonnull__]]
461 find(const _CharT* __str, size_type __pos = 0) const noexcept
462 { return this->find(__str, __pos, traits_type::length(__str)); }
466 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
467 { return this->rfind(__str._M_str, __pos, __str._M_len); }
471 rfind(_CharT __c, size_type __pos = npos) const noexcept;
475 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
477 [[nodiscard, __gnu__::__nonnull__]]
479 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
480 { return this->rfind(__str, __pos, traits_type::length(__str)); }
484 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
485 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
489 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
490 { return this->find(__c, __pos); }
494 find_first_of(const _CharT* __str, size_type __pos,
495 size_type __n) const noexcept;
497 [[nodiscard, __gnu__::__nonnull__]]
499 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
500 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
504 find_last_of(basic_string_view __str,
505 size_type __pos = npos) const noexcept
506 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
510 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
511 { return this->rfind(__c, __pos); }
515 find_last_of(const _CharT* __str, size_type __pos,
516 size_type __n) const noexcept;
518 [[nodiscard, __gnu__::__nonnull__]]
520 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
521 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
525 find_first_not_of(basic_string_view __str,
526 size_type __pos = 0) const noexcept
527 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
531 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
535 find_first_not_of(const _CharT* __str,
536 size_type __pos, size_type __n) const noexcept;
538 [[nodiscard, __gnu__::__nonnull__]]
540 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
542 return this->find_first_not_of(__str, __pos,
543 traits_type::length(__str));
548 find_last_not_of(basic_string_view __str,
549 size_type __pos = npos) const noexcept
550 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
554 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
558 find_last_not_of(const _CharT* __str,
559 size_type __pos, size_type __n) const noexcept;
561 [[nodiscard, __gnu__::__nonnull__]]
563 find_last_not_of(const _CharT* __str,
564 size_type __pos = npos) const noexcept
566 return this->find_last_not_of(__str, __pos,
567 traits_type::length(__str));
573 _S_compare(size_type __n1, size_type __n2) noexcept
575 using __limits = __gnu_cxx::__int_traits<int>;
576 const difference_type __diff = __n1 - __n2;
577 if (__diff > __limits::__max)
578 return __limits::__max;
579 if (__diff < __limits::__min)
580 return __limits::__min;
581 return static_cast<int>(__diff);
585 const _CharT* _M_str;
588#if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
589 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
590 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
592#if __cplusplus > 202002L
593 template<ranges::contiguous_range _Range>
594 basic_string_view(_Range&&)
595 -> basic_string_view<ranges::range_value_t<_Range>>;
599 // [string.view.comparison], non-member basic_string_view comparison function
601 // Several of these functions use type_identity_t to create a non-deduced
602 // context, so that only one argument participates in template argument
603 // deduction and the other argument gets implicitly converted to the deduced
606 template<typename _CharT, typename _Traits>
609 operator==(basic_string_view<_CharT, _Traits> __x,
610 basic_string_view<_CharT, _Traits> __y) noexcept
611 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
613 template<typename _CharT, typename _Traits>
616 operator==(basic_string_view<_CharT, _Traits> __x,
617 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
619 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
621#if __cpp_lib_three_way_comparison
622 template<typename _CharT, typename _Traits>
625 operator<=>(basic_string_view<_CharT, _Traits> __x,
626 basic_string_view<_CharT, _Traits> __y) noexcept
627 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
628 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
630 template<typename _CharT, typename _Traits>
633 operator<=>(basic_string_view<_CharT, _Traits> __x,
634 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
636 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
637 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
639 template<typename _CharT, typename _Traits>
642 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
643 basic_string_view<_CharT, _Traits> __y) noexcept
644 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
646 template<typename _CharT, typename _Traits>
649 operator!=(basic_string_view<_CharT, _Traits> __x,
650 basic_string_view<_CharT, _Traits> __y) noexcept
651 { return !(__x == __y); }
653 template<typename _CharT, typename _Traits>
656 operator!=(basic_string_view<_CharT, _Traits> __x,
657 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
659 { return !(__x == __y); }
661 template<typename _CharT, typename _Traits>
664 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
665 basic_string_view<_CharT, _Traits> __y) noexcept
666 { return !(__x == __y); }
668 template<typename _CharT, typename _Traits>
671 operator< (basic_string_view<_CharT, _Traits> __x,
672 basic_string_view<_CharT, _Traits> __y) noexcept
673 { return __x.compare(__y) < 0; }
675 template<typename _CharT, typename _Traits>
678 operator< (basic_string_view<_CharT, _Traits> __x,
679 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
681 { return __x.compare(__y) < 0; }
683 template<typename _CharT, typename _Traits>
686 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
687 basic_string_view<_CharT, _Traits> __y) noexcept
688 { return __x.compare(__y) < 0; }
690 template<typename _CharT, typename _Traits>
693 operator> (basic_string_view<_CharT, _Traits> __x,
694 basic_string_view<_CharT, _Traits> __y) noexcept
695 { return __x.compare(__y) > 0; }
697 template<typename _CharT, typename _Traits>
700 operator> (basic_string_view<_CharT, _Traits> __x,
701 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
703 { return __x.compare(__y) > 0; }
705 template<typename _CharT, typename _Traits>
708 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
709 basic_string_view<_CharT, _Traits> __y) noexcept
710 { return __x.compare(__y) > 0; }
712 template<typename _CharT, typename _Traits>
715 operator<=(basic_string_view<_CharT, _Traits> __x,
716 basic_string_view<_CharT, _Traits> __y) noexcept
717 { return __x.compare(__y) <= 0; }
719 template<typename _CharT, typename _Traits>
722 operator<=(basic_string_view<_CharT, _Traits> __x,
723 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
725 { return __x.compare(__y) <= 0; }
727 template<typename _CharT, typename _Traits>
730 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
731 basic_string_view<_CharT, _Traits> __y) noexcept
732 { return __x.compare(__y) <= 0; }
734 template<typename _CharT, typename _Traits>
737 operator>=(basic_string_view<_CharT, _Traits> __x,
738 basic_string_view<_CharT, _Traits> __y) noexcept
739 { return __x.compare(__y) >= 0; }
741 template<typename _CharT, typename _Traits>
744 operator>=(basic_string_view<_CharT, _Traits> __x,
745 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
747 { return __x.compare(__y) >= 0; }
749 template<typename _CharT, typename _Traits>
752 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
753 basic_string_view<_CharT, _Traits> __y) noexcept
754 { return __x.compare(__y) >= 0; }
755#endif // three-way comparison
758 // [string.view.io], Inserters and extractors
759 template<typename _CharT, typename _Traits>
760 inline basic_ostream<_CharT, _Traits>&
761 operator<<(basic_ostream<_CharT, _Traits>& __os,
762 basic_string_view<_CharT,_Traits> __str)
763 { return __ostream_insert(__os, __str.data(), __str.size()); }
766 // basic_string_view typedef names
768 using string_view = basic_string_view<char>;
769 using wstring_view = basic_string_view<wchar_t>;
770#ifdef _GLIBCXX_USE_CHAR8_T
771 using u8string_view = basic_string_view<char8_t>;
773 using u16string_view = basic_string_view<char16_t>;
774 using u32string_view = basic_string_view<char32_t>;
776 // [string.view.hash], hash support:
778 template<typename _Tp>
782 struct hash<string_view>
783 : public __hash_base<size_t, string_view>
787 operator()(const string_view& __str) const noexcept
788 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
792 struct __is_fast_hash<hash<string_view>> : std::false_type
796 struct hash<wstring_view>
797 : public __hash_base<size_t, wstring_view>
801 operator()(const wstring_view& __s) const noexcept
802 { return std::_Hash_impl::hash(__s.data(),
803 __s.length() * sizeof(wchar_t)); }
807 struct __is_fast_hash<hash<wstring_view>> : std::false_type
810#ifdef _GLIBCXX_USE_CHAR8_T
812 struct hash<u8string_view>
813 : public __hash_base<size_t, u8string_view>
817 operator()(const u8string_view& __str) const noexcept
818 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
822 struct __is_fast_hash<hash<u8string_view>> : std::false_type
827 struct hash<u16string_view>
828 : public __hash_base<size_t, u16string_view>
832 operator()(const u16string_view& __s) const noexcept
833 { return std::_Hash_impl::hash(__s.data(),
834 __s.length() * sizeof(char16_t)); }
838 struct __is_fast_hash<hash<u16string_view>> : std::false_type
842 struct hash<u32string_view>
843 : public __hash_base<size_t, u32string_view>
847 operator()(const u32string_view& __s) const noexcept
848 { return std::_Hash_impl::hash(__s.data(),
849 __s.length() * sizeof(char32_t)); }
853 struct __is_fast_hash<hash<u32string_view>> : std::false_type
856 inline namespace literals
858 inline namespace string_view_literals
860#pragma GCC diagnostic push
861#pragma GCC diagnostic ignored "-Wliteral-suffix"
862 inline constexpr basic_string_view<char>
863 operator""sv(const char* __str, size_t __len) noexcept
864 { return basic_string_view<char>{__str, __len}; }
866 inline constexpr basic_string_view<wchar_t>
867 operator""sv(const wchar_t* __str, size_t __len) noexcept
868 { return basic_string_view<wchar_t>{__str, __len}; }
870#ifdef _GLIBCXX_USE_CHAR8_T
871 inline constexpr basic_string_view<char8_t>
872 operator""sv(const char8_t* __str, size_t __len) noexcept
873 { return basic_string_view<char8_t>{__str, __len}; }
876 inline constexpr basic_string_view<char16_t>
877 operator""sv(const char16_t* __str, size_t __len) noexcept
878 { return basic_string_view<char16_t>{__str, __len}; }
880 inline constexpr basic_string_view<char32_t>
881 operator""sv(const char32_t* __str, size_t __len) noexcept
882 { return basic_string_view<char32_t>{__str, __len}; }
884#pragma GCC diagnostic pop
885 } // namespace string_literals
886 } // namespace literals
888#if __cpp_lib_concepts
891 // Opt-in to borrowed_range concept
892 template<typename _CharT, typename _Traits>
893 inline constexpr bool
894 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
896 // Opt-in to view concept
897 template<typename _CharT, typename _Traits>
898 inline constexpr bool
899 enable_view<basic_string_view<_CharT, _Traits>> = true;
902_GLIBCXX_END_NAMESPACE_VERSION
905#include <bits/string_view.tcc>
907#endif // __cplusplus <= 201402L
909#endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW